I sprung a leak on the way home from work and have determined that my thermostat (PN# 58335013044) cover has blown a hole through it about the size of my pinky finger nail!! The cap appears to be plastic, and inspection shows it is assymettrically worn on the inside and wore so thin on one side that eventually the water pressure has blown a hole right through it. I will order a new thermostat, but I am worried about how it is wearing (although it IS 10 years old i guess). The inside is also covered with a coating of something with consistency of vaseline - maybe there's oil in the coolant. The coolant is very green and watery - looks normal, and my last oil change showed very good oil. Any comments or is it just old age and new part will fix all. Thanks! Nick.
The cap had to wear somehow and that could only happen from a combo of heat and chemical reaction. It's likely that the plastic used in the cap was ill-chosen and reacted to the glycol and ani-rust agents in the anti-freeze plus the heat. That 'vaseline' like goo was likely liquified/softened cap plastic. I'd check service bulletins for confirmation and then see if a compatible later-model metal cap was available and use it.
one thing to consider with a ten year old bike is. Is there endplay in the bushing? is the pump just worn out? What kind of coolant have you been using? you really need a Aluminum friendly coolant designed not to be corrosive in modern engines. good old green penzoil antifreeze usually just won't cut it. Get silica? free anti freeze.
are you suggesting there could be metal in the coolant from a worn water pump? i didn't want to pull the pump (mostly in fear of what i might find ) but i guess i better inspect it tonight. thanks for the tip on anti-freeze. n.
the least i would do would be change the oil and check for any white filming or slime. the mag drain plug would be a good source for info and I will sometimes tear into my old oil filters and scope them too. but thats alittle anal. ten years old? is it a 620? my book show's the 640 has ball bearings and seals with the shaft driven off the end of the cam. if there is any play in the shaft it will eat the seals. if the anti freeze is old or the wrong kind it might attack the seals. if the seals are bad the bearings are bad therefore... check the pump. tell us the results of the surgery
its a 400 RXC. I haven't checked the oil yet. The water pump has a little bit of play, in the sense that i can turn the fins back and forth a few mm around the shaft (i.e. the normal axis of movement) when the shaft is not moving. there is no play in any other direction. is that ok?
Nick, Bummer to hear you had a problem. Assymetrical wear and chemical reaction do not sound consistent at first blush. That bike has had a hard life. Replace the part , flush coolant/oil etc. watch for anything odd happening. Dagwoods magnetic oil plug is a good idea. I noticed some crap in the screen of mine, pretty sure I just got the biggest peices of flotsum and more is just circulating with the oil. Let us know what you find.
its not a problem vincent! funny part to make out of plastic though :huh the part should arrive on thursday and i'll replace coolant on the weekend. and it's been really fun commuting on my bicycle again!! ps> i did 3 oil changes on your bike before you bought it and never really saw anything in it... even during break in.
You may be right on chemical reaction re; asymetrical attack on cover. However, I did find this on a Jeep site from a Jeep manual: "Antifreeze mixture must always be at least 44%, all climates year round. Maximum protection (-90d) is provided with a 68% mixture protection. If the percentage is lower than 44 percent, engine parts may be eroded by cavitation, and cooling system components may be severely damaged by corrosion" Could it be possible that say x years of the wrong coolant or an incorrect ratio combined with a plastic cap & high temps simply caused errosive cavitation (effectively turbulence)? Expose most plastics to enough heat and chemicals and things have the potential to get ugly. Would not metal particles in the coolant show up in simply draining the coolant through a coffee filter or such? The goo might be plastic residue, hose material It doesn't sound like he has any off-rotational-axis movement of the pump impeller.
That dread green goo. Some more searching may point towards silica in coolant (can't recall where I found it and too lazy to look for it again): --------------------- "The coolant used in modern heavyduty equipment is a complex mixture," says Mr. Christophersen. "It contains chemicals to prevent corrosion, rust and erosion of certain metals, and others to prevent foaming and cavitation. "There also are substances to keep seals from hardening or shrinking, and to prevent freezing. This chemical balance is critical." Two major causes of unbalanced coolant due to improper maintenance are ordinary tap water and high silicate-laden antifreeze. "Depending upon local conditions, it (tap water) can be perfectly acceptable, or can contain minerals that will damage the cooling system," says Mr. Christophersen. "Chemical softening agents that can react badly with coolant chemicals (should be avoided); if your local tap water is 'hard,' use distilled water." A more recent problem, says Mr. Christophersen, is increased use of silicates in antifreeze to protect aluminum cylinder heads, popular in many engines. Because aluminum is more susceptible to corrosion from chemicals in a coolant mix, silicates are added to help protect cylinder heads. "We've been telling the industry for almost three years how to. correct the 'green goo' problem," emphasizes Mr. Christophersen. The "green goo" effect, he explains, comes from silicate dropout, which forms deposits that can wreak havoc with the cooling system. Low-silicate antifreeze is available for heavy-duty use, says Mr. Christophersen." ----- So, do you like your goo green?
Got my new thermostat, also had to order a new hose and a waterpump gasket. Everything is back together and working. But I did notice that the thermostat is just barely oozing a wee bit coolant where it bolts onto the head. There is just an O-ring in there and I bolted it right up dry... was I supposed to apply something to the O-ring before bolting the thermostat on? Its too late in the night to test ride it now to see how bad it leaks under high pressure, but I'm guessing if it oozes at idle it squirts at 5k rpm. Back on the bicycle tomorrow
